Systems and methods for implanting a medical device using an active guidewire

ABSTRACT

Systems and methods for implanting a lead. The system includes an active guidewire having proximal and distal ends. The distal end includes a guidewire anchor that is configured to be attached to a target SOL. The active guidewire is configured to be utilized to electrically map the target SOI by at least one of delivering stimulation energy through the active guide wire to the target SOI or sensing an evoked response at the target SOI from the guidewire. The system also includes a lead having a lead body with proximal and distal ends and with a lumen extending between the proximal and distal ends. The distal end of the lead body is configured to receive the proximal end of the active guidewire. The lumen is configured to permit the lead body to be advanced over the active guidewire.

REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application of, and claimspriority to, U.S. application Ser. No. 17/007,696, Titled “SYSTEMS ANDMETHODS FOR IMPLANTING A MEDICAL DEVICE USING AN ACTIVE GUIDEWIRE” whichwas filed on 31 Aug. 2020, now U.S. Pat. No. 11,529,522 B2, the completesubject matter of which is expressly incorporated herein by reference inits entirety.

BACKGROUND

Embodiments of the present disclosure relate generally to systems andmethods for implanting medical devices within a patient, and moreparticularly to delivery systems for implanting one or more leads.

Cardiac pacemakers and implantable cardioverter-defibrillators (ICD) useinsulated wires (called leads) to monitor the heart and to also deliverelectrical signals or shocks. Various techniques exist for implantingcardiac pacemakers, ICDs, and other medical devices, and each techniquemay use a set of tools designed for that technique. To position a lead,for example, a number of elongated tools (e.g., needles, guidewires,sheaths, and stylets) are inserted into the body. In many cases, thelead is inserted through the lumen of a catheter (or introducer sheath).After the lead is positioned relative to the heart, the catheter isremoved.

Removing the catheter without inadvertently displacing the lead can bechallenging. The leads are thin and, when finally positioned, may have anumber of bends or twists along its path. Furthermore, the proximal endof the lead includes a connector that is larger than the diameter of thesheath's lumen. To address this issue, splittable or peelable sheathsare used. The sheaths are split and separated from each other as thesheaths are withdrawn from the body. As such, the sheaths may be removedwhile avoiding the connector at the proximal end of the lead.

Although these splittable/peelable sheaths are useful, the withdrawalprocess can still be challenging, especially for certain procedures.More recently, the His-Purkinje system has been proposed as aphysiologic substitute for right-ventricle pacing. Recent clinicaltrials demonstrated an increased risk of hospitalization for heartfailure (HF) in patients having a high burden of right-ventricle (RV)pacing and consequently an increased risk of arrhythmias. His-bundlepacing (HBP) uses native conduction pathways and could prevent thenegative effects of RV pacing and promote ventricular synchrony.

It remains challenging, however, to locate the His bundle and achievetrue selective capture. During this procedure, a slittable catheter witha dilator is advanced over a guide wire until the dilator end reachesthe atrium or right ventricle. With the catheter in place, the implanterremoves the guidewire and the dilator and advances a pacing lead throughthe lumen of the catheter. In some cases, the pacing lead accepts astylet to provide rigidity and push-ability to the lead. After thepacing lead is positioned, the catheter is slit and removed, leaving thelead in place.

As discussed above, the implanter is careful when withdrawing thecatheter so that the catheter does not strike the connector at theproximal end and dislodge the lead from its desired position. If thelead is dislodged, the lead-implantation procedure must begin again.Repeating the process increases the risk of infection in addition toother complications that may arise during such medical procedures.

SUMMARY

In accordance with embodiments herein, a system is provided. The systemincludes an active guidewire having proximal and distal ends. The distalend is configured to be located proximate to a target site of interest(SOI) within or proximate to a chamber of the heart. The distal endincludes a guidewire anchor that is configured to be attached to thetarget SOI. The active guidewire is configured to be utilized toelectrically map the target SOI by at least one of deliveringstimulation energy through the active guide wire to the target SOI orsensing an evoked response at the target SOI from the guidewire. Thesystem also includes a lead having a lead body with proximal and distalends and with a lumen extending along the body between the proximal anddistal ends. The distal end of the lead body is configured to receivethe proximal end of the active guidewire. The lumen is configured topermit the lead body to be advanced over the active guidewire until thedistal end of the lead body is proximate the target SOI.

In some aspects, the system also includes an external programmer devicethat can configured to be electrically coupled to the proximal end ofthe active guidewire. The external programmer device may be configuredto electrically map the target SOI.

In some aspects, the target SOI may represent a HIS. The guidewireanchor may be configured to attach the distal end of the activeguidewire into a wall of the heart proximate the HIS. The externalprogrammer device may be configured to deliver a HIS paced event as thestimulation energy and to sense the evoked response to determine whetherHIS capture was achieved based on the His paced event.

In some aspects, the target SOI may represent a left bundle branch. Theguidewire anchor can be configured to attach the distal end of theactive guidewire a predetermined depth into a septa wall that separatesthe right and left ventricles. The external programmer device can beconfigured to deliver the stimulation energy through the distal end ofthe active guidewire to the left bundle branch.

In some aspects, the target SOI may represent a pacing site. Theexternal programmer device may be configured to deliver a pacing pulse,as the stimulation energy, through the guidewire to the target SOI andsense the evoked response at a sensing site within or proximate theheart separate from the pacing site.

In some aspects, the target SOI may represent a sensing site. Theexternal programmer device may be configured to sense the evokedresponse at the sensing site following delivery of a pacing pulse at apacing site within or proximate the heart separate from the sensingsite.

In some aspects, the system also includes a catheter configured to beadvanced to or proximate the chamber of the heart having the target SOI.The catheter may have a lumen with a size dimensioned to receive theactive guidewire. The size of the lumen in the catheter may be smallerthan an outer dimension of the lead body, such that the lead does notfit through the lumen of the catheter.

In some aspects, the catheter may include at least one electrodepositioned proximate to a distal end of the catheter. The at least oneelectrode may be configured to at least one of deliver stimulationenergy to the target SOI or sense an evoked response at the target SOI.

In some aspects, the lead includes a lead anchor coupled to the distalend of the lead body. The lead anchor defines an anchor passage that isaligned with the lumen of the lead body. The anchor passage is sized topermit the lead anchor to slide over the active guidewire as the lumenis advanced over the active guidewire.

In some aspects, the lead anchor includes a helical screw that wrapsabout the anchor passage.

In accordance with embodiments herein, a method of implanting a lead isprovided. The method includes advancing an active guidewire to a targetsite of interest (SOI) within or proximate to a chamber of the heart.The method also includes electrically mapping the target SOI utilizingthe active guidewire by at least one of delivering stimulation energythrough the active guide wire to the target SOI or sensing an evokedresponse at the target SOI from the guidewire. The method also includesfixating a distal end of the active guidewire at the target SOL. Themethod also includes advancing a lead over the active guidewire until adistal end of the lead is located proximate the target SOI.

In some aspects, the fixating the distal end of the active guidewire isperformed before the electrically mapping the target SOI utilizing theactive guidewire.

In some aspects, the target SOI may represent a His bundle region.Fixating the distal end may include attaching the distal end of theactive guidewire into a wall of the heart proximate the His bundleregion. Electrically mapping may include delivering a His paced event asthe stimulation energy. The method may also include assessing whethercapture of the His bundle region was achieved based on the His pacedevent.

In some aspects, the target SOI represents a left bundle branch.Fixating the distal end may include submerging the distal end of theactive guidewire a predetermined depth into a septa wall separating theright and left ventricles. Electrically mapping may include deliveringthe stimulation energy through the distal end of the active guidewire tothe left bundle branch.

In some aspects, the target SOI may represent a pacing site. Theelectrical mapping may include delivering a pacing pulse, as thestimulation energy, through the guidewire to the target SOI and sensingthe evoked response at a sensing site within or proximate the heartseparate from the pacing site.

In some aspects, the target SOI may represent a sensing site. Electricalmapping may include sensing the evoked response at the sensing sitefollowing delivery of a pacing pulse at a pacing site within orproximate the heart separate from the sensing site.

In some aspects, the method also includes, prior to advancing the activeguidewire, advancing a J-tip guidewire, obturator, and catheter to orproximate the chamber of the heart having the target SOI. Prior toadvancing the active guidewire, the method may include withdrawing theobturator and J-tip guidewire. The method also includes inserting theactive guidewire through the catheter to the target SOI and withdrawingthe catheter before advancing the lead over the active guidewire.

In some aspects, advancing the active guidewire may include advancingthe active guidewire through the right atrium and through the rightventricle, forcing the distal end of the active guidewire through asepta wall separating the right and left ventricles, advancing thedistal end of the active guidewire through the left ventricle andsubmerging the distal end of the active guidewire into a wall of theleft ventricle proximate the Purkinje fiber.

In some aspects, the target SOI may represent at least one of an atrialpacing site, a His bundle pacing site, a left bundle branch pacing site,a right bundle branch pacing site, and LV wall pacing site proximate theLV Purkinje fibers.

In some aspects, the method may also include fixating a distal end ofthe lead to tissue at the target SOI and removing the guidewire bywithdrawing the active guidewire along a lumen within the lead.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a heart illustrated in relation to animplantable medical device (IMD) formed in accordance with an embodimentthat includes an implantable lead and a pulse generator interconnectedby a lead adaptor.

FIG. 2 is another schematic view of the heart showing a location of theHis bundle relative to other cardiac structures.

FIG. 3 is a schematic diagram of an IMD formed in accordance with anembodiment that includes an implantable lead, a lead adaptor, and apulse generator.

FIG. 4 is a side schematic view of an active guidewire formed inaccordance with an embodiment.

FIG. 5A is a side view of a delivery system formed in accordance with anembodiment that may be used with the active guidewire of FIG. 4 .

FIG. 5B is an enlarged cross-sectional view of a distal end of acatheter of the delivery system shown in FIG. 5A having a lumen that isconfigured to allow the active guidewire of FIG. 4 to pass therethrough.

FIG. 5C is an enlarged cross-sectional view of a distal end of theimplantable lead of FIG. 3 showing the active guidewire of FIG. 4disposed within a lumen of the implantable lead.

FIG. 6 is a block diagram of a method of implanting a medical device inaccordance with an embodiment that uses the active guidewire of FIG. 5 .

FIG. 7 is a schematic view of a heart having a guidewire advancedtherein in accordance with the method of FIG. 6 .

FIG. 8A illustrates the schematic view of the heart after a catheter hasbeen advanced over the guidewire into the right atrium of the heart.

FIG. 8B illustrates an enlarged view of a distal end of the cathetershown in FIG. 8A after the catheter slides over the guidewire.

FIG. 9A illustrates an enlarged view of the heart after an activeguidewire is inserted through a lumen of the catheter.

FIG. 9B illustrates an enlarged view of the heart after a distal segmentof the active guidewire clears a distal end of the catheter andapproaches a target site-of-interest (SOI).

FIG. 9C illustrates an enlarged view of the heart after the activeguidewire has been fixated to the target SOI.

FIG. 9D illustrates an enlarged view of the heart as the catheter iswithdrawn along the active guidewire while the distal end of the activeguidewire remains fixated to the target SOI.

FIG. 9E illustrates an enlarged view of the heart after the lead hasbeen advanced toward the target SOI along the active guidewire and aftera lead anchor has been fixated to the target SOI.

FIG. 9F illustrates an enlarged view of the heart showing the lead in anoperating position after the active guidewire has been withdrawn througha lumen of the lead.

FIG. 10A is an enlarged view of a heart after a distal segment of anactive guidewire, in accordance with an embodiment, clears a distal endof a catheter and has been fixated to a target SOI in a septa wall ofthe left ventricle.

FIG. 10B is an enlarged view of the heart illustrating a lead in anoperating position after the active guidewire has been withdrawn througha lumen of the lead.

FIG. 11A illustrates a schematic view of the heart after a distal end ofan active guidewire, in accordance with an embodiment, has advancedthrough a septa wall separating the right and left ventricles andsubmerged into a wall of the left ventricle proximate to a target SOI.

FIG. 11B illustrates a schematic view of the heart after a distal end ofa lead, guided by the active guidewire of FIG. 11A, has advanced throughthe septa wall and submerged into the wall of the left ventricle.

FIG. 12 illustrates a block diagram of an exemplary IMD that isconfigured to be implanted into the patient in accordance with one ormore embodiments herein.

DETAILED DESCRIPTION

Embodiments set forth herein include systems for implanting implantablemedical devices (IMDs), assemblies or kits of the systems or IMDs, andmethods for making and using the same. Particular embodiments use anactive guidewire and are implemented in connection with a His-bundlepacing (HBP) strategy or system in which a region of cardiac tissue ator near the His bundle, which is referred to herein as the His bundleregion, is stimulated. Although embodiments may be described in relationto HBP, it should be understood that embodiments may be used inconnection with a variety of IMDs and medical procedures delivering orusing the IMDs. Such procedures may include implanting or extractingleads.

An IMD is a medical device which is intended to be totally or partiallyintroduced into a body (human or animal) and remain in the human bodyafter the procedure. An IMD may include a single component or a systemof components that interact to achieve a desired performance. IMDstypically include at least one active component that perform monitoringand/or therapy functions through electrical energy. Non-limitingexamples of IMDs include a cardiac monitoring device, a pacemaker,cardioverter, cardiac rhythm management device, defibrillator,neurostimulator, and the like. Many IMDs may provide multiple functionsand include implantable cardioverter defibrillators (ICDs) andimplantable cardiac resynchronization therapy/defibrillator devices(CRT-Ds).

IMDs often include a control device (e.g., pulse generator) and one ormore other components that coordinate with the control device. Forexample, cardiac IMDs often include a pulse generator and one or moreleads. The pulse generator has a power source and electronic circuitrythat is configured to monitor the heart. The pulse generator may includeone or more processors that implement programmed instructions (e.g.,software or firmware) stored in memory of the pulse generator. Forexample, the pulse generator may be programmed to provide output stimuli(e.g., signals for pacing or a shock) through the lead or leads.

A lead includes one or more insulated electrical conductors that areintended to transfer electrical energy along a length of the lead. Forexample, the lead may transfer output stimuli from the pulse generatoror transmit depolarization potentials from cardiac tissue to a sensingcircuit of the pulse generator. A lead typically includes a lead bodyhaving an elongated flexible tube or sleeve comprising, for example, abiocompatible material (e.g., polyurethane, silicone, etc.). The lead(or lead body) has a distal end and a proximal end. As used herein, theterms “proximal” and “distal,” when used in reference to a lead (orother elongated instruments, such as an introducer sheath, catheter,guidewire, or stylet) are to be understood in relation to delivering andimplanting a medical device. During an implantation procedure,“proximal” is to be understood as relatively close to the implanter and“distal” is to be understood as relatively far away from the implanter.After the implantation, a proximal end of a lead is coupled to a pulsegenerator, and a distal end of the lead is positioned adjacent to tissue(e.g., cardiac or nerve tissue).

The lead body may include a single lumen (or passage) or multiple lumen(or passages) within the flexible tube. A lead may have multipleelectrical conductors (not shown) that electrically couple electrode(s)of the lead to the pulse generator. The electrical conductors may becabled conductors coated with PTFE (poly-tetrafluoroethylene) and/orETFE (ethylenetetrafluoroethylene). The electrical conductors areterminated to the respective electrode. The lead body may be configuredfor receiving a guide wire or stylet that enable positioning of thelead.

The lead may include one or more electrodes or one or more contactsthrough which electrical energy may leave or enter the conductors of thelead. Electrodes may be positioned adjacent to tissue for monitoring orproviding therapy thereto. The lead connector also includes one or morecontacts that are communicatively coupled to the one or more electrodes.The lead adaptor and the pulse generator are also described as includingcontacts. To more readily distinguish electrodes and contacts, theelectrodes can be described as being positioned at the distal end andthe contacts can be described as being positioned at the proximal end ofthe lead or as part of a lead adaptor or a pulse generator.

Various types of electrodes and contacts exist, including tip electrodesor contacts, ring electrodes or contacts, contact pads, patchelectrodes, spring electrodes, or porous electrodes. Electrodes andcontacts may also have a variety of configurations or patterns (e.g.,unipolar, bipolar or multi-polar, array, etc.). In particularembodiments, the electrodes/contacts may be arranged according tointernational standard 1 (IS-1) that are used for low-voltageapplications. The configuration may be unipolar or bipolar. A largestdimension of an IS-1 lead connector is 3.2 mm.

The lead adaptor enables an electrical and mechanical connection betweenthe lead connector and the pulse generator. The lead adaptor may be usedto upsize or downsize the lead connector in order to mate with the pulsegenerator. Optionally, the lead adaptor may also function as a leadextender that effectively increases the length of the lead.

Leads also include a lead connector positioned at the proximal end. Thelead connector provides an electrical connection between the one or moreelectrodes of the lead and the one or more contacts of a control device(e.g., pulse generator). As described herein, the lead connector canalso mate with a lead adaptor. The lead adaptor may then mate with thepulse generator to electrically connect the electrodes to the pulsegenerator and mechanically connect the lead to the pulse generator.

A lead may be delivered and positioned relative to tissue using acatheter (or introducer sheath). A catheter is a tube or cannula that isintroduced into the body (e.g., through the vascular system, forexample), typically over another elongated instrument, such as a needle,dilator, or guidewire. The catheter includes a lumen that permitspassage of other elongated instruments, such as the lead. The cathetermay form part of a delivery system (or kit) that includes one or moreother elongated instruments, such as a needle, a guidewire, a syringe, adilator, and one or more other sheaths.

In particular embodiments, the catheter is non-splittable ornon-peelable. In such embodiments, the catheter may be removed while theactive guidewire is secured to a target SOI. With the catheter removed,an implantable lead may be guided to the target SOI using the activeguidewire. In addition to using non-splittable or non-peelablecatheters, particular embodiments may enable catheters having asmaller-sized lumen as it is not necessary for the lumen to accommodatethe implantable lead.

FIG. 1 illustrates a schematic cutaway view of a heart 10 relative to anIMD 50. The heart 10 includes a right atrium RA, a right ventricle RV, aleft atrium LA, and a left ventricle LV. During normal operation of theheart 10, deoxygenated blood from the body is returned to the rightatrium RA from the superior vena cava 12 and inferior vena cava 14. Theright atrium RA pumps the blood through the atrioventricular ortricuspid valve 16 to the right ventricle RV, which then pumps the bloodthrough the pulmonary valve 18 and the pulmonary artery 20 to the lungsfor reoxygenation and removal of carbon dioxide. The newly oxygenatedblood from the lungs is transported to the left atrium LA, which pumpsthe blood through the mitral valve 22 to the left ventricle LV. The leftventricle LV pumps the blood through the aortic valve 24 and the aorta26 throughout the body.

FIG. 2 is another schematic cutaway view of the heart 10 showing alocation of the bundle of His 30 in the heart. The bundle 30 consists offast-conducting muscle fibers that begin at the atrioventricular node inthe right atrium and pass to the interventricular septum. The bundle 30divides in the septum into a right branch that travels along the rightside of the septum and supplies excitation to the right ventricle, and apair of left branches that travel along the left side of the septum andsupply excitation to the left ventricle. The fibers in the branchesterminate in an extensive network of Purkinje fibers which distributeexcitation pulses to the layer of cells beneath the endocardium.

Returning to FIG. 1 , the IMD 50 includes a pulse generator 52 that isoperably coupled to an implantable lead 54 through a lead adaptor 56.The lead adaptor 56 is configured to receive a lead connector (notshown) of the lead 54. Although the IMD 50 includes only one lead inFIG. 1 , a number of other leads (e.g., two, three, four, etc.) may beused. The lead 54 is designed to penetrate the endocardium in contactwith His bundle 30. The lead 54 may enter the vascular system throughone of several possible vascular access sites and extends through thesuperior vena cava 12 to the right atrium RA.

In FIG. 1 , the IMD 50 is a cardiac pacemaker. In other embodiments,however, the IMD 50 may include an ICD, a CRT-D, an ICD coupled with apacemaker, and the like. The IMD 50 may be a dual-chamber stimulationdevice capable of treating both fast and slow arrhythmias withstimulation therapy, including cardioversion, defibrillation, and pacingstimulation, as well as capable of detecting heart failure, evaluatingits severity, tracking the progression thereof, and controlling thedelivery of therapy and warnings in response thereto. The IMD 50 may becontrolled to sense atrial and ventricular waveforms of interest,discriminate between two or more ventricular waveforms of interest,deliver stimulus pulses or shocks, and inhibit application of astimulation pulse to a heart based on the discrimination between thewaveforms of interest and the like.

Although not shown, the IMD 50 may wirelessly communicate with anexternal device. For example, the external device may initiate the pulsegenerator 52. The external device and the pulse generator maycommunicate identification data (e.g., obtain model and serial number)between one another. The external device may generate a chart thatcorrelates to the patient having the pulse generator 52. The externaldevice may instruct the pulse generator 52 to perform an electrodeintegrity check and measure parameters of the electrodes (e.g.,impedance of shock electrode(s)). The external device and/or the pulsegenerator may determine a sensing configuration for the pulse generatorbased on cardiac activity. During initiation of the pulse generator 52,therapy parameters may be selected by the user of the external device.

FIG. 3 is a schematic diagram of a system 100, which is hereinafterreferred to as an implantable medical device (IMD) 100. The IMD 100 isnot assembled in FIG. 3 . In some embodiments, the IMD 100 may begrouped or packaged as a set or kit. The IMD 100 includes an implantablepulse generator 102 and a lead assembly 104. The pulse generator 102 hasa connector cavity 103 that is configured to mate with the lead assembly104. The lead assembly 104 includes an implantable lead 106 and a leadadaptor 108. The lead 106 includes a lead body 107 that extendslengthwise along a longitudinal axis 111 between a distal end 110 and aproximal end 112. The term longitudinal axis encompasses both linear andnon-linear axes. For example, the longitudinal axis 111 may extend alonga curved path that changes as the lead body 107 is flexed, bent,twisted, or otherwise manipulated.

The lead body 107 includes a lumen 115 extending along the lead body 107between the proximal and distal ends 112, 110. The longitudinal axis 111may extend through a geometric center of the lead body 107. The distalend 110 of the lead body 107 is configured to receive a proximal end(not shown) of an active guidewire, such as the active guidewire 150(shown in FIG. 5 ). The lumen 115 is configured to permit the lead body107 to be advanced over the active guidewire until the distal end 110 ofthe lead body 107 is proximate a target SOI.

The lead 106 may include a plurality of electrodes 120, 122 positionedat the distal end 110. The electrodes 120, 122 are arranged in a bipolarconfiguration but other configurations may be used. The lead 106 alsohas a lead connector 124 positioned at the proximal end 112. The leadconnector 124 includes a portion of the lead body 107 and lead contacts126, 128 that are communicatively coupled to the electrodes 120, 122through a plurality of conductors (not shown) that are contained withinthe lead body 107. In the illustrated embodiment, the lead body 107 isiso-diametric such that a diameter of the lead 106 is essentiallyuniform throughout. The iso-diametric body 107 may permit a catheter(not shown) to slide over the lead connector 124 when the catheter isremoved.

Various combinations of the electrodes and contacts may be used inconnection with sensing cardiac signals and/or delivering stimulationtherapies. For example, the electrodes 120, 122 include a tip electrode120 and a ring electrode 122, and the lead contacts 126, 128 include atip contact 126 and a ring contact 128. In other embodiments, however,the electrodes and contacts may include any number ofelectrodes/contacts and have a variety of types or shapes.

As described herein, the lead body 107 may have a body outer envelopethat is configured to fit within a lumen of a catheter and the leadconnector 124 has a connector outer envelope configured to fit withinthe lumen of the catheter. The lead body 107 includes an insulatingsheath or housing of a suitable insulative, biocompatible, biostablematerial such as, for example, silicone rubber or polyurethane,extending substantially the entire length of the lead body andsurrounding the conductors.

The lead adaptor 108 is configured to interconnect the implantable lead106 and the pulse generator 102. As shown, the lead adaptor 108 has aninsertable connector 132 that includes mating contacts 134, 136. Thelead adaptor 108 also includes and an adaptor cavity 138 that includescavity contacts. The cavity contacts are positioned to engage the leadcontacts 126, 128 of the lead connector 124 when the lead connector 124is inserted into the adaptor cavity 138 of the lead adaptor 108. Theinsertable connector 132 is configured to be inserted into the connectorcavity 103 of the pulse generator 102.

FIG. 4 is a schematic side view of an active guidewire 150 formed inaccordance with an embodiment. The active guidewire 150 includes aproximal end 152 and a distal end 154 and a wire body (or core) 156 thatextends between the proximal and distal ends 152, 154. The wire body 156may comprise, for example, stainless steel, nickel-titanium alloy(Nitinol), or the like.

The active guidewire 150 is configured to be communicatively coupled toan external programmer device 170. The external programmer device isconfigured to electrically map the target SOI. To this end, the externalprogrammer device 170 includes one or more processors and memory thatstores program instructions directing the processors to performelectrical mapping operations. For example, one or more processors ofthe device may control the external programmer device 170 to deliverstimulation energy through the active guide wire to the target SOI. Oneor more processors of the device may control the external programmerdevice 170 to sense an evoked response at the target SOI from the activeguidewire.

The external programmer device 170 is configured to locate a target siteof interest (SOI) of tissue, such as a target SOI within or proximate toa chamber of the heart. The target SOI may be a pacing site or a sensingsite. The target SOI may represent at least one of an atrial pacingsite, a HIS pacing site, a left bundle branch pacing site, a rightbundle branch pacing site, and LV wall pacing site proximate the LVPurkinje fibers.

The proximal end 152 of the active guidewire 150 may be directly orindirectly coupled to the external programmer device 170 as shown inFIG. 4 . In some embodiments, the proximal end 152 may be directlycoupled to a terminal of the external programmer device 170.Alternatively, the proximal end 152 may be directly coupled to atransmitter that communicates with the external programmer device 170.The external programmer device 170 may receive mapping data in the formof electrical signals that are transmitted through the active guidewire150.

The active guidewire 150 may include a coil 158 that is wrapped aboutthe wire body 156. As shown in FIG. 5 , the coil 158 is wrapped about adistal segment 160 of the active guidewire 150 that includes the distalend 154. In particular embodiments, the distal segment 160 of the activeguidewire 150 has a designated shape.

The active guidewire 150 also includes a fixation anchor 162. In theillustrated embodiment, the fixation anchor 162 is shaped such that,when directed toward the target SOI and rotated about a central axis,the fixation anchor 162 is driven into the tissue, thereby affixing thedistal end 154 to the tissue. The designated shape of the distal segment160 may decrease the likelihood that the fixation anchor 162inadvertently engages or snags other tissue while the active guidewire150 is advanced through the body. For example, the distal segment 160may yield a J-shaped tip when the distal segment 160 is in an unbiasedstate.

In some embodiments, the active guidewire 150 has an average operatingdiameter 164 that is between 0.040″ and 0.025″. The average workingdiameter is a diameter of the active guidewire that is inserted into thebody or, more particularly, inserted into the heart. In certainembodiments, the active guidewire 150 has an average operating diameter164 that is between 0.036″ and 0.028″ or, more particularly, between0.034″ and 0.030″.

The coil 158 and/or the fixation anchor 162 may have a cross-sectionalshape that is circular, oval-like, or ribbon-like. The coil 158 and/orthe fixation anchor 162 may comprise discrete elements or may be shapedfrom the same piece of material. For example, a wire that defines thecoil 158 and/or the fixation anchor 162 may comprise a stiff metalhaving a high shear modulus. For example, the wire may include platinum,platinum iridium alloy, 304 stainless steel, 316 stainless steel, 316Lstainless steel, or the like. The wire may have an outer diameter thatis between 0.003″ and less than 0.011″ or, more specifically, between0.004″ and less than 0.010″. In particular embodiments, the wire has anouter diameter that is between 0.005″ and less than 0.009″.

Optionally, the active guidewire 150 may include one or more coatings165. For example, the one or more coatings 165 may include anelectrically-insulative coating, such as parylene, PTFE, ethylenetetrafluoroethylene (ETFE), or the like. Optionally, the one or morecoatings 165 may include a hydrophobic or hydrophilic coating along aportion or an entirety of the wire to reduce the friction between theguidewire 150 and the lead. A lumen of the lead may include an innersurface comprising polytetrafluoroethylene, ETFE, or the like. Forexample, the lumen may be defined by a cylindrical core comprisingpolytetrafluoroethylene, ETFE, or the like. In some embodiments, thelead is similar or identical to one or more embodiments described inU.S. Pat. No. 9,623,235, which is hereby incorporated by reference inits entirety.

The fixation anchor 162 is electrically active such that fixation anchormay function as an electrode. For example, the fixation anchor 162 mayform part of a conductive pathway that is configured for at least one ofpacing or sensing electrical activity of the tissue. The fixation anchor162 may also be used for mapping. By way of example, a length of thefixation anchor 162 may be at least 1.0 mm. In some embodiments, thefixation anchor 162 has a length that enables a deeper penetration intotissue. In particular embodiments, the fixation anchor 162 has a lengthbetween 2.0 mm and 5.0 mm that is configured to reach into septal tissueto achieve left or right bundle branch block correction. Optionally,when the fixation anchor 162 is greater than 2.00 mm a portion of thefixation anchor may be coated with parylene so that the proximity of thetarget tissue may be more precisely identified.

The fixation anchor 162 may be configured to sense electrical activityto identify the target SOI. Sensing with the fixation anchor 162 may beachieved in a unipolar mode while sensing between fixation anchor 162and a remote electrode (not shown). The remote electrode may be, forexample, a surgical clamp positioned at the pocket or incision.

Alternatively, a local electrogram may be obtained by using one or moreelectrodes positioned at a distal end of a catheter. For example, thedistal end may include a pair of electrodes. If the electrode pairdetects the designated site of tissue, it may not be necessary to useboth the electrode pair and the fixation anchor 162 for mapping. Undersome circumstances, it may be uncertain whether the His potential isfrom the electrode pair 104 or the guidewire fixation screw 112.

For some implementations, the target SOI may represent a left bundlebranch (LBB). The fixation anchor 162 may be configured (e.g., sized,shaped, and oriented) to attach the distal end 154 of the activeguidewire 150 to the target SOI. The fixation anchor 162 may enableachieving a predetermined depth into a septa wall that separates theright and left ventricles. In such embodiments, the external programmerdevice 170 may deliver stimulation energy through the distal end 154 ofthe active guidewire 150 to the LBB.

For other implementations, the target SOI represents a pacing site andthe external programmer device 170 is configured to deliver a pacingpulse, as the stimulation energy, through the guidewire 150 to thetarget SOI. The external programmer device 170 may sense the evokedresponse at a sensing site within or proximate the heart in which thesensing site is separate from the pacing site.

Yet in other implementations, the target SOI represents a sensing siteand the external programmer device is configured to sense the evokedresponse at the sensing site following delivery of a pacing pulse at apacing site within or proximate the heart that is separate from thesensing site.

FIG. 5A is a side view of a delivery system 200 formed in accordancewith an embodiment. The delivery system 200 includes a catheter (orintroducer sheath) 202, a handle 204, a connector assembly 206, and afluid flushing assembly 208. Each of these components may be similar oridentical to components described in greater detail in U.S. applicationSer. No. 16/452,223, filed on Jun. 25, 2019, and U.S. application Ser.No. 16/907,515, filed on Jun. 22, 2020, each of which is incorporatedherein by reference in its entirety.

The connector assembly 206 includes an electrical connector 210 coupledto a trailing end of handle 204. The electrical connector 210 iselectrically coupled to one or more electrodes along the catheter 202.For example, FIG. 5B is an enlarged cross-sectional view of a distalsegment 224 of the catheter 202 as identified by the dashed circle inFIG. 5A. In the illustrated embodiment, the electrical connector 210(FIG. 5A) is communicatively coupled to electrodes 270, 272 (FIG. 5B)and optionally an electrode 274 (FIG. 5B) through conductors 280 thatare embedded within the catheter 202. The electrodes 270, 274 areproximate to a distal tip (or end) 227 of the catheter 202. Inparticular embodiments, the electrodes 270, 272 are split-ringelectrodes. The connector assembly 206 is configured to communicativelycouple to an electrogram mapping system (not shown).

As shown in FIG. 5A, the handle 204 may include a hemostasis hub 212 foraccepting and coupling to (e.g., tethering to) a proximal end of thecatheter 202. The catheter 202 has a catheter lumen 282 (FIG. 5B) thatis sized to receive a guidewire, such as the guidewires 305 (FIG. 9A),307 (FIG. 7 ). The hemostasis hub 212 includes an entrance that permitsaccess to the catheter lumen 282. The fluid flushing assembly 208 isalso configured to mechanically couple to the hemostasis hub 212 andfluidly couple to the catheter lumen 280 through the hemostasis hub 212.

The catheter 202 is configured to introduce a guidewire and/or lead intoa designated anatomical region (e.g., a patient's heart). Optionally,the catheter 202 may be steerable so that an end of the distal endsegment 224 may be located proximate to and face the target SOI. To thisend, the catheter 202 may include a plurality of sheath segments orportions. For example, the catheter 202 may include a proximal segment221, a body segment 222, a deflectable segment 223, and the distal endsegment 224. Based on its intended use, the catheter 202 may beconfigured to exhibit various properties. For example, the catheter maybe maneuverable and have a sufficient columnar strength for beinginserted through a tortuous vascular system. The catheter may also havesufficient kink-resistance so as to bend smoothly. Multiple layers ofthe catheter may be configured to have these and other properties.

The delivery system 200 may also include an obturator/dilator 220. InFIG. 5A, a proximal end 292 of the obturator/dilator 220 is shown and adistal end 225 of the obturator/dilator 220 is also shown. The distalend 225 may be wedge-shaped or cone-shaped (e.g., conical). As discussedbelow, the obturator/dilator 220 is configured to enlarge an opening foraccess to the vascular system and/or to provide support for the catheter202 as the catheter 202 is being maneuvered.

FIG. 5C is an enlarged cross-sectional view of the distal end 110 of theimplantable lead 106. The lumen 115 of the implantable lead 106 may havea diameter 119 that is sized to allow the active guidewire 150 to passtherethrough. For example, the lumen 115 of the implantable lead 106 mayhave a proximal opening (not shown) and a distal opening 121 that aresized relative to the active guidewire 150 so that the active guidewire150 may move through each of the openings. For example, the distalopening 121 may be sized to allow the fixation anchor 162 and at least aportion of the coil 158 to pass therethrough.

The tip electrode 120 may constitute a fixation anchor that isconfigured to fixate with tissue at the target SOI. The tip electrode120 may also be sized relative to the active guidewire 150. For example,the tip electrode 120 may define an anchor passage 123 that is alignedwith the lumen 115 of the lead body 107. The anchor passage 123 may havea diameter DP that is sized to permit the tip electrode 120 to slideover the active guidewire 150 (or vice versa) as the active guidewire150 slides through the lumen 115. More specifically, the anchor passage123 and the wire body 156 are configured so that the implantable lead106 may be inserted over the proximal end (not shown) of the activeguidewire 150 and advanced along the active guidewire 150 toward thetarget SOI. Likewise, the fixation anchor 162 of the active guidewire150 and the anchor passage 123 of the tip electrode 120 are configuredso that the fixation anchor 162 may pass through the anchor passage 123as the active guidewire 150 is withdrawn from the target SOI. Forexample, the diameter DP may be between 0.025″ and 0.045″ or, moreparticularly, between 0.030″ and 0.040″.

Also shown in FIG. 5C, the tip electrode 120 has a length LA. The lengthLA may be increased or decreased based on the target SOI. For example,the length LA may be increased to reach His bundles or bundle branchesthat are greater than 2.0 millimeters below the endocardial surface. Insuch embodiments, a proximal end of the tip electrode 120 (e.g., endthat is closer to the lead body) may be coated with an insulatingmaterial, such as parylene, to maintain the impedance of the tipelectrode within a desired range for pacing electrodes. Likewise, thetip electrode 120 may be configured based upon the tissue near thetarget SOI to ensure that the tip electrode 120 may reach a desiredregion within the target SOI. For example, the diameter of the wire thatdefines the tip electrode 120 may be increased or may have a materialselected for its particular application.

FIG. 6 is a flowchart illustrating a method 450 of positioning animplantable lead with respect to cardiac tissue. The method 450 isdescribed with reference to FIGS. 7-14 . The method 450 is illustratedin the context of HBP but may be suitable for other procedures.Particular embodiments utilize an electrically-active mapping guidewirewith active fixation for use with a HIS-bundle implantation catheter.The systems and methods may promote normal conduction through theHIS-Purkinje system. Pacing at the bundle of His may prevent thenegative effects of RV pacing and promote ventricular synchrony.

With reference to FIG. 7 , a guidewire 307 is inserted through an accesspoint of the vascular system. In some embodiments, the guidewire 307 isa catheter-positioning guidewire that is intended to be removed after acatheter is positioned within a designated space of the vascular systembut prior to the lead being affixed to tissue. As such, the guidewire307 may not be an active guidewire. In other embodiments, however, theguidewire 307 may be an active guidewire that may be used to positionthe catheter within the designated space and also to identify a locationof a target SOI 303.

The guidewire 307 has a distal segment 310. Optionally, the distalsegment 310 may have a predetermined shape to aid positioning of theguidewire 307. For example, the distal segment 310 may provide aJ-shaped distal end or tip of the guidewire 307. As the guidewire 307 isnavigated through the vascular system, the curved distal segment 310 mayreduce the likelihood of the guidewire 307 inadvertently snagging orengaging other tissue.

The access point may be created by a needle (not shown) that is insertedthrough an incision of the body and into the vascular system. Thisprocess may be similar to the Seldinger technique. For example, a venousneedle stick may be inserted through the subclavian vein or anothervein, thereby creating an access point. After identifying the vein, theguidewire 307 may be inserted, at 425 (FIG. 6 ), through the accesspoint and into the vascular system. The guidewire 307 is directed into apredetermined region of the vascular system having a target SOI 303.

The guidewire 307 and the distal segment 310 in particular may be guidedand positioned within the chamber using medical imaging. For example,the guidewire 307 may be tracked using fluoroscopy. As shown in FIG. 7 ,the distal segment 310 may be directed into a chamber of the hearthaving the target SOI 303. In FIG. 7 , the chamber is the right atrium312. In other embodiments, however, the chamber may be the rightventricle 314.

Turning to FIGS. 8A and 8B, with the distal segment 310 positionedwithin the designated chamber, a catheter 301 can be inserted throughthe access point. The catheter 301 is advanced, at 454 (FIG. 6 ), alongthe guidewire 307. The catheter 301 may include features that aresimilar or identical to the catheter 202 (FIG. 5A) and may be controlledby a delivery system, such as the delivery system 200 (FIG. 5A).

Optionally, the catheter 301 may include an obturator/dilator 220 withina lumen 322 of the catheter 301. The obturator/dilator 220 may alsoinclude a passage (not shown) through which the guidewire 307 mayextend. The obturator/dilator 220 can have a wedge-shaped or cone-shapeddistal end 225 that aids in enlarging the access point. When initiallyinserted through the access point, the catheter 301 may have asubstantially straight configuration and may include theobturator/dilator 220 positioned at or near the distal end of thecatheter 301 to enlarge the access point and to provide support for thecatheter 301 as it is being maneuvered. The straight configuration ofthe catheter 301 may aid its passage through the superior vena cava andinto the right atrium. Upon entry into the vein, the implanter mayremove the obturator/dilator 220 and advance the catheter 301 over theguidewire 307 to the right atrium 312. Alternatively, the guidewire 307may be removed before or after the obturator/dilator 220 is removed oralong with removing the obturator/dilator 220.

Once a distal end 324 (FIG. 8B) of the catheter 301 has entered theright atrium 312, the catheter 301 may be further advanced toward thetarget SOI 303. For embodiments in which the guidewire 307 remains, thecatheter 301 slides over the distal segment 310 and the distal segment310 may be partially deflected. For example, the J-shaped distal segment310 may partially straighten while also causing the catheter 301 tocurve toward the target SOI 303. Alternatively, the distal end 324 ofthe catheter 301 may be steered within the right atrium 312 by theimplanter without assistance from the guidewire 307.

For embodiments in which the catheter-positioning guidewire 307 is used,the method 450 (FIG. 6 ) may also include replacing thecatheter-positioning guidewire 307 with an active guidewire 305 (shownin FIG. 9B). After removing the catheter-positioning guidewire 307, anactive guidewire 305 may then be inserted, at 455, through the lumen 322and advanced toward the target SOI 303 as guided by the catheter 301. At456 (FIG. 6 ), the distal end 324 of the catheter 301 may be positionedadjacent to tissue having the target SOI 303. Although FIG. 6 indicatesthat the catheter 301 is positioned adjacent to the tissue afterinserting the active guidewire 305, it should be understood that thecatheter 301 may be positioned prior to the active guidewire 305 beinginserted or as the active guidewire 305 is inserted.

FIG. 9A shows a distal end 320 of the active guidewire 305 disposedwithin the lumen 322 of the catheter 301. The distal end 320 includes afixation anchor 330. In FIG. 9A, the active guidewire 305 is in aretracted position such that a tip of the fixation anchor 330 is locatedwithin the lumen 322 and the catheter 301 surrounds the entirety of thefixation anchor 330. In the retracted position, the fixation anchor 330may not be aligned with or not co-located with electrodes 332, 334 ofthe catheter 301. For example, the fixation anchor 330 may be positionedat a depth 336 that is measured between a tip of the fixation anchor 330and a tip of the distal end 324 of the catheter 301 (or an end of thelumen 322). The depth 336 may be configured such that electrodes 332,334 of the catheter 301 are positioned closer to the target SOI 303 andsuch that the conductive material of the fixation anchor 330 does notinterfere with the electrodes 332, 334 ability to detect electricalsignals and/or supply electrical current.

FIG. 9B shows the distal end 320 of the active guidewire 305 in aprojected (or protracted) position. In the projected position, thefixation anchor 330 may be pressed against a surface of the target SOI303. In FIG. 9B, the surface is the endocardial surface of the rightatrium. The fixation anchor 330 may be positioned at a clearance (or aseparation distance) 338 that is measured between the fixation anchor330 and the tip of the distal end 324 of the catheter 301. The clearance338 may be configured such that the fixation anchor 330 is positioned infront of the electrodes 332, 334 and closer to the target SOI 303. Theclearance 338 may be configured to improve detection of electricalsignals from the target SOI during a mapping operation. For example, theclearance 338 may be configured to improve sensing between the activeguidewire fixation anchor electrode 330 and 332 and/or 334 electrodes.

FIG. 9C shows the distal end 320 of the active guidewire 305 fixated totissue of the target SOI 303. To secure the fixation anchor 330, theimplanter may rotate the active guidewire 305 while pressing thefixation anchor 330 into the surface. The fixation anchor 330 may piercethe tissue and forces provided by rotating the fixation anchor 330 andpressing the fixation anchor 330 forward may drive the fixation anchor330 into the tissue.

At any of the configurations and spatial relationships shown in FIGS.9A, 9B, and 9C, the target SOI 303 may be electrically mapped toidentify a more precise location for implanting a lead. In particularembodiments, the target SOI 303 includes the His bundle. For mostindividuals, the His bundle is located within a membranous portion ofthe interventricular septum. A portion of the proximal bundle may existwithin a right atrial portion of the septum superior to the tricuspidvalve annulus. At this location, the His bundle may be surrounded byfibrous connective tissue. Within the right ventricular portion of theseptum, the His bundle divides to form the right and left bundles.

The target SOI may be electrically mapped, at 258, by (a) the catheter301 alone, (b) a combination of the catheter 301 and the activeguidewire 305, or (c) the active guidewire 305 only. Optionally, themapping process may include detecting signals from only two of (a), (b),or (c) or include detecting signals from each of (a), (b), or (c). Insome embodiments, the mapping process may only include detecting signalsfrom either (b) or (c) or from each of (b) and (c). For example, undercontrol of one or more processors configured with specific executableinstructions, an external programmer device may deliver stimulationenergy through at least one of the catheter or the active guide wire tothe target SOL. Alternatively or in addition to delivering stimulationenergy, the external programmer device may sense an evoked response atthe target SOI from at least one of the catheter or the activeguidewire.

Returning to FIG. 9A, the distal end 324 of the catheter 301 may besteered toward the target SOI. In some embodiments, the target SOI 303may be initially mapped (or approximately located) using the electrodes332, 334 of the catheter 301. Sensing between 332 and 334 provides asmall dipole that allows for precisely targeting a site proximate theHis or bundle branch, the SOI 330. The implanter may operate a deliverysystem, such as the delivery system 200 (FIG. 5A), to position thedistal end 324 of the catheter 301. Deflecting the catheter 301 may beaccomplished by an actuator (e.g., actuator 235 shown in FIG. 5A) thatis operably coupled to segments (e.g., segments 221-223 shown in FIG.5A). With a proximal segment of the catheter 301 positioned in thesuperior vena cava, the actuator may move a deflectable segment of thecatheter 301 such that a distal end 324 of the catheter 301 will pointgenerally toward a wall surface 335. The wall surface 335 may be, forexample, the surface of an atrial wall proximate to where the target SOIis believed to be located. The distal end 324 may be in close proximityto the septum, such as within 15 millimeters or less.

An external programmer device may be configured to be electricallycoupled to a proximal end of the catheter 301. The catheter 301 maycommunicate electrical signals between the external programmer deviceand the electrodes 332, 334 for electrically mapping the target SOI 303.For example, the electrodes 332, 334 may sense electrical signals andcommunicate these electrical signals to the external programmer devicefor electrically mapping the target SOI 303. In such instances, it maybe desirable to position the fixation anchor 330 at least the depth 336within the lumen 322. If electrical signals are received from theelectrodes 332 and 334, the implanter may know that the distal end 324of the catheter 301 is at least approximately aligned with the targetSOI 303.

If the electrodes 332, 334 are not receiving electrical signals, or ifthe signals are very faint, the implanter may maneuver the distal end324 of the catheter 301 by small movements of the actuator (e.g., ineither a forward or reverse direction) to scan the atrial wall asindicated by the dashed arrows in FIG. 9A. The small movements of theactuator will deflect the deflectable section of the catheter 301 bysmall amounts. A surface point 340 (shown in FIG. 9B) may be identifiedwhen the signals received by the electrodes 332, 334 are strongest.

Alternatively or in addition to using the catheter 301, the surfacepoint 340 may be identified using the fixation anchor 330 of the activeguidewire 305. More specifically, the fixation anchor 330 may be pressedagainst a series of points along the wall surface 335. When against thewall surface 335, the active guidewire 307 may at least one of deliverstimulation energy or detect an evoked response.

The point having the strongest signal may be designated as the surfacepoint 340 through which the fixation anchor 330 will be submerged.Optionally, the electrical mapping may occur in unipolar mode by sensingbetween the fixation anchor 330 and a remote electrode (not shown), suchas a surgical clamp at the pocket. In other embodiments, the electricalmapping may occur by sensing between the fixation anchor 330 and atleast one of the electrodes 332, 334. The external programmer device maybe communicatively coupled to the active guidewire 305 so that theelectrical programmer device may receive signals sensed by the activeguidewire 305.

Accordingly, the surface point 340 may be generally located by mappingwith the catheter 301 to identify a local region along the wall surface335 and then more precisely located by measuring a series of pointswithin this local region to identify the surface point 340.Alternatively, the surface point 340 may be identified by mapping onlywith the catheter 301. In such instances, the surface point 340 may beany point within the local region identified by the catheter 301. As yetanother alternative embodiment, the surface point 340 is identified,without initially mapping, by measuring a series of points along thewall surface 335.

FIG. 9C shows the fixation anchor 330 after piercing through the surfacepoint 340 and submerging within the tissue of the target SOI 303. Withthe surface point 340 identified, the method includes fixating, at 460(FIG. 6 ), the distal end 324 of the active guidewire 305 to the targetSOI 303. More specifically, the fixation anchor 330 may be pressedagainst the wall surface 335 as the active guidewire 305 is rotated. Inaddition to urging the fixation anchor 330 into the tissue, therotational force provided to the fixation anchor 330 by the implanterfurther drives the active guidewire 305 into the tissue. At 462 (FIG. 6), additional measurements may be acquired to assess whether capture ofthe target SOI 303 has been achieved. These measurements may be acquiredat different depths within the tissue.

At 464 (FIG. 6 ), the catheter 301 may be withdrawn. As shown in FIG.9D, the active guidewire 305 may remain embedded within the tissue ofthe target SOI 303. At 466 (FIG. 6 ), an implantable lead 456 (FIG. 9E)may be advanced over the active guidewire 305. More specifically, aproximal end of the active guidewire 305 may inserted into a lumen 365(FIG. 9E) of the implantable lead 356. The implantable lead 356 may beinserted through the access point and urged toward the target SOI whiletracking along the active guidewire 305.

FIG. 9E shows a lead anchor 370 of the implantable lead 356 fixated tothe tissue of the target SOI. With the fixation anchor 330 of the activeguidewire 305 remaining secured to the target SOI, a lead anchor 370 ofthe implantable lead 356 is guided to the surface point 340. At 468(FIG. 6 ), the lead anchor 370 may be fixated to the tissue that isproximate the target SOI 303. Similar to the fixation anchor 330, thelead anchor 370 may be pressed against the wall surface 335 as theimplantable lead 305 is rotated. In addition to urging the lead anchor370 into the tissue, the rotational force provided to the lead anchor370 by the implanter drives the lead anchor 370 into the tissue.

FIG. 9F shows the implantable lead 356 in an operating position with thelead anchor 370 functioning as a tip electrode of the implantable lead356. At 470, the lead anchor 370 may sense electrical activity from thetarget SOI 303 to verify capture of the target SOI 303. The fixationanchor 330 may also be used at this time to verify capture. In FIG. 9F,the target SOI is the His bundle.

At 472, the active guidewire 305 may be withdrawn. For example, theimplanter may gently pull the active guidewire 305 while also rotatingthe active guidewire 305 in an opposition direction. As described withrespect to FIG. 5C, the active guidewire 305 may be removed through ananchor passage (not shown) of the lead anchor 370.

FIGS. 10A and 10B illustrate another embodiment of the method 450, (FIG.6 ) in which a target SOI 403 is one of the bundle branches located inthe septum wall between the right and left ventricles. As shown in FIG.10A, a fixation anchor 430 of an active guidewire 405 is capable ofdriving greater depths into the septum wall. In such instances, acatheter 401 may provide additional support to the active guidewire 405.For example, the active guidewire 405 at the surface point 440 may beheld straight by the catheter 401 so that the force applied by theimplanter does not cause the active guidewire 405 to bend or kink. Forembodiments in which the target SOI 403 has greater depths, such as thedepths where bundle branches may be located, the implantable lead 456may be driven to greater depths using lead anchors 470 have greaterlengths. As described herein, such lead anchors may be coated with aninsulating material to control impedance.

FIGS. 11A and 11B illustrate another embodiment of the method 450 (FIG.6 ) in which a target SOI 503 is located on an opposite side of a septumwall 507. In such instances, the target SOI 503 is proximate thePurkinje fiber through the opposite left ventricle wall. In alternativeembodiments, the target SOI is identified as 513 and is located on anopposite side of a septum wall 517 proximate to the Bachmann's bundle.The following is with reference to the septum wall 507 and the Purkinjefiber but may be similarly applied to the septum wall 517 and theBachmann's bundle.

As shown in FIG. 11A, the active guidewire 505 may be driven through theseptum wall 507, through the left ventricle, and into the septum wallthat includes the Purkinje fiber. The active guidewire 505 may identifythe target SOI 503 and whether it has been located as described abovewith respect to the target SOI 303. Accordingly, in some embodiments,the active guidewire 505 may be advanced through the right atrium andthrough the right ventricle. The distal end of the active guidewire 505may be forced through the septa wall 507 separating the right and leftventricles, advanced through the left ventricle, and submerged into awall of the left ventricle proximate the Purkinje fiber.

As shown in FIG. 11B, an implantable lead 556 may be advanced along theactive guidewire 505, through the septum wall 507, and into the leftventricle. After the lead anchor 570 is submerged within the wall, theactive guidewire 505 may be removed. In other embodiments, however, thecatheter 501 may be removed and the active guidewire 505 may remain andfunction as a pacing lead. In such embodiments, the implantable lead 556is not used.

FIG. 12 illustrates a block diagram of an exemplary IMD that isconfigured to be implanted into the patient in accordance withembodiments herein. The IMD 600 may treat both fast and slow arrhythmiaswith stimulation therapy, including cardioversion, pacing stimulation,an implantable cardioverter defibrillator, suspend tachycardiadetection, tachyarrhythmia therapy, and/or the like.

The IMD 600 has a housing 661 to hold the electronic/computingcomponents. The housing 661 (which is often referred to as the “can,”“case,” “encasing,” or “case electrode”) may be programmably selected toact as the return electrode for certain stimulus modes. The housing 661further includes a connector (not shown) with a plurality of terminals601, 602, 604, 606, 608, and 610. The terminals may be connected to oneor more leads that are located in various locations within and about theheart. Each lead may have one or more electrodes. The type and locationof each electrode may vary. For example, the electrodes may includevarious combinations of ring, tip, coil, shocking electrodes, and thelike.

The IMD 600 includes a programmable microcontroller 620 that controlsvarious operations of the IMD 600, including cardiac monitoring andstimulation therapy. The microcontroller 620 includes a microprocessor(or equivalent control circuitry), one or more processors, RAM and/orROM memory, logic and timing circuitry, state machine circuitry, and I/Ocircuitry. The IMD 600 further includes a pulse generator 622 thatgenerates stimulation pulses for connecting the desired electrodes tothe appropriate I/O circuits, thereby facilitating electrodeprogrammability. The switch 626 is controlled by a control signal 628from the microcontroller 620.

Optionally, the IMD 600 may include multiple pulse generators, similarto the pulse generator 622, where each pulse generator is coupled to oneor more leads/electrodes and controlled by the microcontroller 620 todeliver select stimulus pulse(s) to the corresponding one or moreelectrodes. The IMD 600 includes sensing circuit 644 selectively coupledto one or more electrodes that perform sensing operations, through theswitch 626 to detect the presence of cardiac activity in the chamber ofthe heart. The output of the sensing circuit 644 is connected to themicrocontroller 620 which, in turn, triggers, or inhibits the pulsegenerator 622 in response to the absence or presence of cardiacactivity. The sensing circuit 644 receives a control signal 646 from themicrocontroller 620 for purposes of controlling the gain, threshold,polarization charge removal circuitry (not shown), and the timing of anyblocking circuitry (not shown) coupled to the inputs of the sensingcircuit 624.

In the example of FIG. 12 , the sensing circuit 644 is illustrated.Optionally, the IMD 600 may include multiple sensing circuits 644, whereeach sensing circuit is coupled to one or more leads/electrodes andcontrolled by the microcontroller 620 to sense electrical activitydetected at the corresponding one or more electrodes. The sensingcircuit 624 may operate in, for example, a unipolar sensingconfiguration or a bipolar sensing configuration.

The IMD 600 further includes an analog-to-digital (A/D) data acquisitionsystem (DAS) 650 coupled to one or more electrodes via the switch 626 tosample cardiac signals across any pair of desired electrodes. The A/Dconverter 650 is configured to acquire intracardiac electrogram signals,convert the raw analog data into digital data and store the digital datafor later processing and/or telemetric transmission to an externaldevice 690 (e.g., a programmer, local transceiver, or a diagnosticsystem analyzer). The A/D converter 650 is controlled by a controlsignal 656 from the microcontroller 620.

The microcontroller 620 is operably coupled to a memory 660 by asuitable data/address bus 662. The programmable operating parametersused by the microcontroller 620 are stored in the memory 660 and used tocustomize the operation of the IMD 600 to suit the needs of a particularpatient. The operating parameters of the IMD 600 may be non-invasivelyprogrammed into the memory 660 through a telemetry circuit 664 intelemetric communication via communication link 667 (e.g., MICS,Bluetooth low energy, and/or the like) with the external device 690.

The IMD 600 can further include one or more physiological sensors 670.Such sensors are commonly referred to as “rate-responsive” sensorsbecause they are typically used to adjust pacing stimulation ratesaccording to the exercise state of the patient. However, thephysiological sensor 670 may further be used to detect changes incardiac output, changes in the physiological condition of the heart, ordiurnal changes in activity (e.g., detecting sleep and wake states).Signals generated by the physiological sensors 670 are passed to themicrocontroller 620 for analysis. While shown as being included withinthe IMD 600, the physiological sensor(s) 670 may be external to the IMD600, yet still, be implanted within or carried by the patient. Examplesof physiological sensors might include sensors that, for example, senserespiration rate, pH of blood, ventricular gradient, activity,position/posture, minute ventilation, and/or the like.

A battery 672 provides operating power to all of the components in theIMD 600. The battery 672 is capable of operating at low current drainsfor long periods of time, and is capable of providing a high-currentpulses (for capacitor charging) when the patient requires a shock pulse(e.g., in excess of 2 A, at voltages above 2 V, for periods of 10seconds or more). The battery 672 also desirably has a predictabledischarge characteristic so that elective replacement time can bedetected. As one example, the IMD 600 employs lithium/silver vanadiumoxide batteries.

The IMD 600 further includes an impedance measuring circuit 674, whichcan be used for many things, including sensing respiration phase. Theimpedance measuring circuit 674 is coupled to the switch 626 so that anydesired electrode and/or terminal may be used to measure impedance inconnection with monitoring respiration phase. The IMD 600 is furtherequipped with a communication modem (modulator/demodulator) 640 toenable wireless communication with other devices, implanted devicesand/or external devices. In one implementation, the communication modem640 may use high frequency modulation of a signal transmitted between apair of electrodes. As one example, the signals may be transmitted in ahigh frequency range of approximately 10-80 kHz, as such signals travelthrough the body tissue and fluids without stimulating the heart orbeing felt by the patient.

Optionally, the microcontroller 620 may control a shocking circuit 680by way of a timing control 632. The shocking circuit 680 generatesshocking pulses as controlled by the microcontroller 620. The shockingcircuit 680 may be controlled by the microcontroller 620 by a controlsignal 682.

Although not shown, the microcontroller 620 may further include otherdedicated circuitry and/or firmware/software components that assist inmonitoring various conditions of the patient's heart and managing pacingtherapies. The microcontroller 620 further includes a timing control632, an arrhythmia detector 634, a morphology detector 636 andmulti-phase therapy controller 633. The timing control 632 is used tocontrol various timing parameters, such as stimulation pulses (e.g.,pacing rate, atria-ventricular (AV) delay, atrial interconduction (A-A)delay, ventricular interconduction (V-V) delay, etc.) as well as to keeptrack of the timing of RR-intervals, refractory periods, blankingintervals, noise detection windows, evoked response windows, alertintervals, marker channel timing, and the like.

The morphology detector 636 is configured to review and analyze one ormore features of the morphology of cardiac activity signals. Forexample, in accordance with embodiments herein, the morphology detector636 may analyze the morphology of detected R waves, where suchmorphology is then utilized to determine whether to include or excludeone or more beats from further analysis. For example, the morphologydetector 636 may be utilized to identify non-conducted ventricularevents, such as ventricular fibrillation and the like.

The arrhythmia detector 634 may be configured to apply one or morearrhythmia detection algorithms for detecting arrhythmia conditions. Byway of example, the arrhythmia detector 634 may apply various detectionalgorithms. The arrhythmia detector 634 may be configured to declare aventricular fibrillation episode based on the cardiac events.

The therapy controller 633 is configured to perform the operationsdescribed herein. The therapy controller 633 is configured to identify amulti-phase therapy based on the ventricular fibrillation episode, themulti-phase therapy including a pacing therapy. The therapy controller633 is configured to manage delivery of the burst pacing therapy at apacing site in a coordinated manner after the one or more shocks. Thepacing site may be located at a target SOI, such as a His Bundle.Optionally, other pacing sites may be located at one of a leftventricular (LV) site or a right ventricular (RV) site. The therapycontroller 633 may configured to manage delivery of the shock along ashocking vector between shocking electrodes.

Reference throughout this specification to “one embodiment” or “anembodiment” (or the like) means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment. Thus, appearances of the phrases “in oneembodiment” or “in an embodiment” or the like in various placesthroughout this specification are not necessarily all referring to thesame embodiment.

It is to be understood that the above description is intended to beillustrative, and not restrictive. For example, the above-describedembodiments (and/or aspects thereof) may be used in combination witheach other. In addition, many modifications may be made to adapt aparticular situation or material to the teachings of the inventivesubject matter without departing from its scope. While the dimensionsand types of materials described herein are intended to define theparameters of the inventive subject matter, they are by no meanslimiting and are exemplary embodiments. Many other embodiments will beapparent to one of ordinary skill in the art upon reviewing the abovedescription. The scope of the inventive subject matter should,therefore, be determined with reference to the appended claims, alongwith the full scope of equivalents to which such claims are entitled. Inthe appended claims, the terms “including” and “in which” are used asthe plain-English equivalents of the respective terms “comprising” and“wherein.” Moreover, in the following claims, the terms “first,”“second,” and “third,” etc. are used merely as labels, and are notintended to impose numerical requirements on their objects. Further, thelimitations of the following claims are not written inmeans-plus-function format and are not intended to be interpreted basedon 35 U.S.C. § 112(f) unless and until such claim limitations expresslyuse the phrase “means for” followed by a statement of function void offurther structure.

What is claimed is:
 1. A system, comprising: at least one of a guidewireor catheter with a distal end configured to be located within a chamberof a heart proximate to a sight of interest (SOI) at a septal wall; alead having a proximal end and a distal end, the lead configured to beadvanced along at least one of the guidewire or the catheter to the SOI;one or more electrodes located at a distal end of at least one of thecatheter, guidewire or lead, at least a first electrode from the one ormore electrodes configured to be inserted to different depths into theseptal wall at the SOI; a pulse generator configured to generatestimulation energy; and one or more processors that, when executingprogram instructions, are configured to electrically map a target depthwithin the septal wall by at least one of: directing the pulse generatorto deliver stimulation energy to the first electrode, as pacing pulses,when the first electrode is inserted to the corresponding differentdepths within the septal wall; or sensing evoked responses at thecorresponding different depths within the septal wall when the firstelectrode is inserted to the corresponding different depths within theseptal wall.
 2. The system of claim 1, wherein the one or moreprocessors, when executing the program instructions, are configured todelivery first and second pacing pulses when the electrode is at firstand second depths, respectively, in the septal wall.
 3. The system ofclaim 1, wherein the electrode represents an anchor configured to beinserted into the septal wall to the target depth proximate to one of aHIS, a left bundle branch (LBB), or a right bundle branch (RBB), thetarget depth based on one or both of the stimulation energy or evokedresponses at the corresponding different depths.
 4. The system of claim3, wherein the target depth is proximate to the HIS, the first electroderepresents an anchor provided at a distal end of the guidewire, theanchor is electrically coupled to the pulse generator, and the one ormore processors configured to deliver HIS paced events as the pacingpulses and to sense the evoked responses to determine whether HIScapture was achieved based on the HIS paced events.
 5. The system ofclaim 3, wherein the target depth is proximate to the LBB, the firstelectrode represents an anchor provided at a distal end of theguidewire, the is anchor electrically coupled to the pulse generator,and the anchor is configured to be inserted, at the SOI in the septalwall, to the target depth at the LBB to deliver the pacing pulses to theLBB.
 6. The system of claim 3, wherein the target depth is proximate tothe HIS, the first electrode represents an anchor provided at a distalend of the lead, the anchor is electrically coupled to the pulsegenerator, and the one or more processors is configured to deliver HISpaced events as the pacing pulses and to sense the evoked responses todetermine whether HIS capture was achieved based on the HIS pacedevents.
 7. The system of claim 3, wherein the target depth is proximateto the LBB, the first electrode represents an anchor provided at adistal end of the lead, the anchor is electrically coupled to the pulsegenerator, and the anchor is configured to be inserted, at the SOI inthe septal wall, to the target depth at the LBB to deliver the pacingpulses to the LBB.
 8. The system of claim 1, wherein the one or moreelectrodes further comprises a catheter electrode provided at a distalend of the catheter and the first electrode represents an anchorprovided at the distal end of one of the guidewire or lead.
 9. Thesystem of claim 1, wherein the electrical mapping includes deliveringthe stimulation energy through the one or more electrodes to the leftbundle branch.
 10. The system of claim 1, further comprising an at leastone of external programmer device or an implantable medical device thatincludes the pulse generator, the lead including a proximal end coupledto at least one of the external programmer device or implantable medicaldevice.
 11. A method, comprising: advancing at least one of a guidewireor catheter into a chamber of a heart proximate to a sight of interest(SOI) at a septal wall; advancing a lead along at least one of theguidewire or the catheter to the SOI until a distal end of the lead isproximate to the SOI, at least one of the catheter, guidewire or leadhaving a distal end that includes one or more electrodes; inserting afirst electrode from the one or more electrodes to different depths intothe septal wall at the SOI; utilizing one or more processors toelectrically map a target depth within the septal wall by at least oneof: directing a pulse generator to deliver stimulation energy to thefirst electrode, as pacing pulses, when the first electrode is insertedto the corresponding different depths within the septal wall; ordirecting sensing circuitry to sense evoked responses at thecorresponding different depths within the septal wall when the firstelectrode is inserted to the corresponding different depths within theseptal wall.
 12. The method of claim 11, wherein the electrical mappingfurther comprising delivering first and second pacing pulses when theelectrode is at first and second depths, respectively, in the septalwall.
 13. The method of claim 11, wherein the electrode represents ananchor, the method further comprising inserting the anchor into theseptal wall to the target depth proximate to one of a HIS, a left bundlebranch (LBB), or a right bundle branch (RBB), and basing the targetdepth on one or both of the stimulation energy or evoked responses atthe corresponding different depths.
 14. The method of claim 13, whereinthe target depth is proximate to the HIS, the first electrode representsan anchor provided at a distal end of the guidewire, and the anchor iselectrically coupled to the pulse generator, the method furthercomprising delivering HIS paced events as the pacing pulses and sensingthe evoked responses to determine whether HIS capture was achieved basedon the HIS paced events.
 15. The method of claim 13, wherein the targetdepth is proximate to the LBB, the first electrode represents an anchorprovided at a distal end of the guidewire, and the anchor iselectrically coupled to the pulse generator, the method furthercomprising inserting the anchor, at the SOI in the septal wall, to thetarget depth at the LBB to deliver the pacing pulses to the LBB.
 16. Themethod of claim 13, wherein the target depth is proximate to the HIS,the first electrode represents an anchor provided at a distal end of thelead, and the anchor is electrically coupled to the pulse generator, themethod further comprising delivering HIS paced events as the pacingpulses and sensing the evoked responses to determine whether HIS capturewas achieved based on the HIS paced events.
 17. The method of claim 13,wherein the target depth is proximate to the LBB, the first electroderepresents an anchor provided at a distal end of the lead, the anchor iselectrically coupled to the pulse generator, the method furthercomprising inserting the anchor, at the SOI in the septal wall, to thetarget depth at the LBB to deliver the pacing pulses to the LBB.
 18. Themethod of claim 11, wherein the one or more electrodes further comprisesa catheter electrode provided at a distal end of the catheter and thefirst electrode represents an anchor provided at the distal end of oneof the guidewire or lead.
 19. The method of claim 11, wherein theelectrical mapping includes delivering the stimulation energy throughthe one or more electrodes to the left bundle branch.
 20. The method ofclaim 11, further comprising: obtaining measurements of cardiacactivity; assessing whether capture of the SOI is achieved based on themeasurements; and selecting the target depth based on the assessment ofcapture.